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JOHN NICHOLS, or BATTLE CREEK-MICHIGAN.-

Letters Patent No. 91,658, dated June 22, 1869.

IMPROVEMENT IN THRESHINQMACHINB CONCAVB.

v The Schedule alerted to in these Letters Patent and making part0! the sanie.

To all whom it may concern:

Be it known that I, J 01m NrcnoLs, of Battle Creek, county of Calhoun, and State of Michigan, have inventeda new and useful Improvement in Threshing- Machine Ooncaves, of which the following is a full,

clear, and exact description, reference being had to the accompanying drawings, making a part of this specification, in which- Figure 1 is a plan or top view of the concave. Figure 2 is avertical section through the same, in line a: a', fig. ll.

Similar leters of reference denote corresponding parts wherever used.- It is a fact well understood by those familiar with the working of threshing-machines, that owing to the diflerence of kinds and conditions of grain required tube operated upon, a machine which operates well and efiiciently upon a certain kind, or a certain condition of diii'erent kinds oi grain, is very defective in. its operation when employed for threshing a different kind-of grain or the same kind of grain under adifi'ecent condition.

For example, where the grain is in goodcondition, w'ell cured, and the straw is straight, the grain may be readily 'fed to, and will be eii'ectirely operated upon, by most of the various machines in use; but it fre, qnentlyhappens, where I-the grain .is tangled, that it is a'ditficnlt task to feed it properly to the machine, and, as a consequence, the grain-being presented in tangled masses or bundles,the machine becomes choked,

and the operation is suspended until the cylinder can be cleared.

Again, where the grain is thoroughly dry, the ma chine may work with case, but where it is wet or tough, it has frequently been found almost impossihis to make the machine operate upon-it at all satisfactorily.

My invention has for. its object the remedying of these diliicnlties and (lefects; and' relates to a novel construction and arrangement of parts, whereby the machine may be readily adapted to the kind or condition of grain to be operated'upon; to this end,

"-The invention consists in making the crnoave in removable sections,'one of which is made blank, and adapted to he transferred from a position in front to one intermediate between, or behind the toothed sec-l tions, as the conditions of the grain may require. If it is preferred, the two sections maybe made in one piece, and the desired change in the adaptation of the machine made by reversing the position of the section thus formed, or any other arrangement may be introduced which will accomplish the same object.

In the accompanying drawings.

a A represeptsa frame, of any usual or suitable construc'tion, in crosspieces a a, in the upper part of which is mounted the concave, composed of grooved or flanged supporting-sides B, adapted to receive and to support the toothed and peribratedconeave bed B',;which, in this instance, is composed of removable blank section b and toothed sections 1) b, a. stationary blank section, b, and removable apron orbed board if.

' These sections may be of any desired-number consistent with the required strength, and the concave, as

a whole, may conform in its constructionto those in :ordinary use.

The grooves in theside plates B'are curved, and made to conform to-or nearly to the arc of a circle, of which the axis of the cylinder (not shown in drawing) is the centre, and the sections 5 b, conforming in shape thereto, slide into said grooves, and maybe readily removed, and their relative position changed, as the condition of the grain may require lhe removable apron b alsofits in grooves in the front of the sides B, and is removed when it-is desired to change the sections; I

When in position, the several sections are sustained against the action of the cylinder by stationary sections b..-

Thegrcoved or fianged sides 18 have pivotal supports, at b, in the main frame, upon which, as a centre, the concave may be adjusted or vibrated, to bring it nearer or tomove it away fromthe cylinder, This good condition," and where the feeding-and threshing of the grain'is easily eii'ected, the blank section b may be placed next to the stationary section b; then, by the adjustment of the forward or apron-endjof the concave,- the, teeth of the concave and threshing-cylinder may bemade" to interlock to a greater or less extent, and thereby to act with the required force upon the grain, while all unnecessary injury to the straw may be avoided.

- Where the grain is tougher wet, it is sometimes found desirable to give the teeth an intermediate space, in which to clear themselves, and thereby prevent the clogging of the machine. In this case the blank sections should be placed between the toothed sections.

Where the grain is tangled and difiicult tolfeed, the blank section should be placed-next to the feed-board or apron (2, so as to form a curved extension thereof, conforming to the direction of movement of the teeth otfthe cylinder, and said teeth are thereby enabled to seize and carry forward the grain to the point of threshing, thereby assisting in the operation of feed- "he operation of the other parts of the machine will be understood without further description.

What I claim as new, and desire to secure by Letters Patent, is-

1. A concave, composed of removable sections, for

the purpose set forth.

2. The removable blank section of the concave, adapted to be transposed relative to the toothed sections, supported at their ends-in grooved or flanged side pieces, substantially a s-and for the purpose sen Witn Psses Ens. Nxonons, Dsvu) Swarm. 

